Spring 2023 has finally arrived. Once again this year it falls on March 20 (at 10.24 pm, Italian time). After all, the last time we celebrated the spring equinox on the traditional date of March 21st was in 2007; not only that: the vernal equinox will continue to fall on March 20 until 2102.
Man adapts to the changes of season thanks to a brain nucleus made up of about 20,000 neurons, rather small if we consider that an average brain contains about 86 billion neurons and another 85 billion non-neuronal cells. It is the suprachiasmatic nucleus, one of the groups of neurons that form the hypothalamus, a structure located at the base of the brain. It can be defined as our internal clock, so much so that an injury to it compromises the sleep-wake cycle. Indeed, it is here that circadian rhythms are regulated, i.e. the psycho-physiological changes over a 24-hour period, from metabolism to body temperature.
Matter of light. It is he who orchestrates the organism’s adaptation to the variations of daylight with the alternation of the seasons. By studying the brain of mice, which works in a similar way to the human one, some scientists at the University of California, San Diego, have observed that, according to the light, its neurons change the type and quantity of neurotransmitters, influencing the activity brain and consequently daily behaviors. Information is sent to them by specialized cells in the retina.